What to expect from the first US presidential debate between Trump and Harris

United States presidential candidates Donald Trump and Kamala Harris will both be looking for an advantage when they meet for their first televised debate on Tuesday (Sep 10) evening.
The debate, which carries high stakes for both, is expected to be watched by millions and could give either contender an edge in the race for the White House.
It comes just a few months after Trump’s debate with US President Joe Biden, which sparked concerns over the latter’s age and cognition, leading to calls for his withdrawal from the race. 
Biden dropped his re-election bid several weeks later and endorsed Vice President Harris to succeed him.
“Traditionally, political science research suggests that general election debates aren’t all that consequential. But now we have one that’s hugely consequential,” said analyst Jacob Smith, an assistant professor of political science at Fordham University.
With less than two months to go until Americans go to the ballot box on Nov 5, Tuesday’s debate – to be broadcast on ABC News – remains the only scheduled presidential debate so far.
It also comes as Harris is riding high on a wave of momentum, fuelled by a Democratic Party energised by the change of candidate.
National polls show former president Trump trailing Harris by as much as 5 per cent. In contrast, he was leading Biden by a similar amount before their debate in June.
Both Trump and Harris have a history of flip-flopping on issues. They will be pushed for a precise stance on policies during the debate. 
Trump has made vague promises including the mass deportation of undocumented immigrants, despite research suggesting the move will crater the US economy and reduce the country’s gross domestic product by around 2.6 per cent.
But he has since softened his position by suggesting foreign graduates should receive green cards.
Trump has also distanced himself from the highly detailed, almost 1,000-page conservative platform known as Project 2025, which has been billed as a policy “wish list” for the next Republican president to overhaul the government’s executive branch.
He has embraced the popular short-video app TikTok as well as cryptocurrency, both of which he had previously vehemently opposed.
Meanwhile, Harris has changed her stance on issues such as no longer supporting a ban on fracking and becoming more hardline on border security.
However, she has laid out little in the way of foreign policy plans.
Experts previously told CNA that Harris – who is the country’s first female, Black and South Asian vice president – is expected to continue Biden’s foreign policies in Asia if she wins the election.
Observers said Harris needs to convey her vision of America’s future to voters.
“Everybody knows who Donald Trump is. They’ve had four years of living under him,” noted Todd Belt, director of political management at George Washington University.
“What is it that Harris wants to do? She has talked very vaguely about a few ideas that she has. She needs to put more flesh on the bones.”
Bryan DeAngelis, who is partner and head of global communications and stakeholder solutions firm Penta Group’s Washington office, agreed that the pressure is on Harris to show Americans what kind of president she will be.
Trump will have to “try to stay disciplined … and not tip into some of the chaos that tends to turn voters off”, he told CNA’s Asia First programme on Tuesday.
“There are a number of issues that will work to (Harris’) advantage – certainly abortion, some of the other economic issues – but there’s also a feeling in the US that the economy isn’t going as well as it could be going,” DeAngelis said.
“She’ll have a lot of questions to answer about what she’ll do differently from Biden when it comes to her running the economy.”
Observers also said things have visibly changed for Trump’s campaign since Biden withdrew from the race.
“Trump is clearly feeling a little more desperate than he was back in June and July. He’s been throwing out a lot of different policy proposals – there’s almost a kind of whiplash,” said Kyle Kondik, managing editor of Sabato’s Crystal Ball, a political newsletter run by the University of Virginia’s Center for Politics.
The major issue of age has also put Trump at a disadvantage.
With 82-year-old Biden out of the running, Trump will become the oldest US president to ever take office should he win the election.
On the debate stage, his 78 years are likely to draw a stark contrast to Harris’ 59 years. 
Nevertheless, DeAngelis said that rather than age, Harris is likely to focus on Trump’s criminal cases and the controversial issues that arose from his presidency.
Vice President Harris was a prosecutor and former California attorney general, while Trump was president between 2017 and 2021, and a businessman and media personality. He is also the first person to run for the White House as a convicted felon.
“She’s really trying to create a contrast between what we saw for Trump for four years – and even the four years he’s been out of office – with her vision for the future … I think she’ll come right out of the gate looking to make that case against him,” said DeAngelis.
Both campaigns have agreed that the candidates’ microphones will remain muted while the other is speaking, meaning there will be no interruptions.
“You have two very similar candidates in how they approach debates. Both of them like to get under the skin of the other one … so I anticipate this will be a very tense debate,” said George Washington University’s Belt.